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Recent discoveries have given rise to a new class of electronics known as "spin electronics" or "spintronics," which uses the electron spin rather than its charge to create polarized currents. Spintronics is currently experiencing an extraordinary development with the manufacture of nanoscale devices based on ferromagnetic materials and semiconductors. Their applications are numerous, ranging from recording, electronics, and optoelectronics to quantum information. Spintronics is a new generation of electronics that has brought and continues to bring a lot of progress to information storage; this is due to the discovery of new materials with new functionalities and multiple applications. The discovery of giant magnetoresistance (GMR) in 1988 by Albert Fert and Peter GrÃ"nberg (receiver of the Nobel Prize in Physics in 2007) is considered a starting point of spintronics. GMR is based on the variation of the electric current in the presence of a magnetic field. The spintronics has made important contributions to the miniaturization desired for electronics; it uses nanometric components for processing and storing information. However, the limits of miniaturization on a nanometric scale are known, and it is imperative to develop new ways and new materials to exceed those limits. The most desired properties for these materials are high spin polarization, modular magnetic properties by an electric field and a long lifetime of the spin polarization. Among the new promising materials, we cite the following: Diluted magnetic semiconductors, which give new magnetic properties of conventional semiconductors, functional oxides (including the semi-metals and multiferroic metals) and organic semiconductors. The main theoretical challenge in this area is to understand how the macroscopic magnetic behavior observed results from interactions of a large number of degrees of microscopic freedom. In these systems the disorder is an essential parameter of magnetic phenomena, and due to random locations of impurity atoms it can lead to a total physical difference from the observed absence. There has been considerable recent advances in the design of these materials as diluted magnetic semiconductors (DMS, or diluted magnetic semiconductors), and a number of semiconductors were investigated as II-VI group and III-V group doped compounds, with transition metals substituting their original cations. There are several different theoretical approaches to study these magnetic materials. The ab-initio approach starts from the Schrödinger equation to simulate a given material. Such an approach is essential to determine the parameters and microscopic properties of such a system. In this book, the authors analyzed the electronic structure of magnetic semiconductors diluted in the case of ZnO, GaN, SnO2, TiO2, MgH2, EuO and EuN doped RENs (RE=GdN, DyN and HoN). The authors focused on magnetic, optical and exchange mechanisms which control the ferromagnetism in these systems. The purpose of this book is to propose some ideas to answer the most important question in material science for semiconductor spintronics, primarily considering how room-temperature ferromagnetism in DMS can be realized. Additionally, the correlation between first principle and experimental design to see how properties of yet-to-be-synthesized materials can be predicted is discussed.

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While arthroplasty is the preferred treatment for most elderly patients with displaced femoral neck fractures, internal fixation is the treatment of choice in the majority of patients below the age of 65 as a joint-preserving procedure. The osteosynthesis of fractures of the femoral neck in the elderly has been partly abandoned during the last years due to the poor clinical outcomes following the conventional fixation with parallel screws or DHS. Based on clinical evidence and laboratory testing, the novel method of biplane double-supported screw fixation (BDSF) offers much better fixation stability, reflecting in excellent clinical outcomes. With its innovative biomechanic principle, the BDSF method provides supreme stability for cannulated screw fixation, achieving up to 44% higher axial fixation strength in vitro, and a rate of bone union reaching up to 96.6% in clinical practice, which is much higher than the conventional parallel screw fixation data. The method of BDSF provides supreme stability by buttressing two out of three medially diverging cannulated screws on the inferior femoral neck cortex and supporting the steeper inferior screw on the posterior femoral neck cortex. The two calcar screws are oriented in different coronal inclinations intended to provide constant fixation strength during different patient activities and load directions. Biomechanically, the most effective component is the inferior screw placed at an obtuse angle and supported on a large area along the inferior and posterior cortex of the femoral neck following its spiral anterior curve. Given the clinical outcomes, BDSF is the perfect technique for femoral neck fracture fixation, as the fracture healing rate is high at 96% with this approach. Therefore, BDSF is not only a treatment alternative to conventional fixation, but also a much better procedure. Thus, BDSF should be routinely applied, and conventional fixation gradually abandoned in clinical practice (this has been the approach in our institution over the last ten years). This book describes the full surgical technique of the method of BDSF for femoral neck fracture osteosynthesis; quality criteria and surgical recommendations for successful BDSF implementation, according to the vast clinical experience of ten years with this highly effective method. A novel surgical approach for hip arthroplasty is described in this book. The current trends aimed at decreasing operative trauma and blood loss have been not entirely satisfied with respect to most of the standard approaches for hip arthroplasty. These surgeries are often associated with considerable blood loss and the necessity for restricting patients' activities in the postoperative period due to impaired joint stability and risk of dislocations. This book describes the full surgical technique of the novel anatomical direct lateral approach for hip arthroplasty, aimed at decreasing blood loss, minimizing operative trauma, and optimizing joint stability. This technique is associated with minimal blood loss and high joint stability. Patients are allowed to perform activities within the normal range of motion in the early postoperative period. This book describes also the history of internal fixation in femoral neck fractures, as well as the biomechanics of femoral neck fracture osteosynthesis and the role of the implants.

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